Screw compressor

Abstract

A screw compressor including a driving machine having an output shaft coupled to an input shaft of a compressor main body; a clutch mechanism between the output shaft of the driving machine and the input shaft of the compressor main body; a pressure sensor installed in a discharge channel; and a controller that controls the switching of the clutch mechanism between an engaged state and a disengaged state based on a discharge pressure value detected by the pressure sensor is disclosed. When the discharge pressure value becomes higher than an unload set value that is predetermined, the controller controls the clutch mechanism to be switched to the disengaged state. According to the above screw compressor, power losses are reduced even when the supply of compressed gas is hardly required.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a screw compressor, especially relates to a screw compressor that effectively reduces power losses during unload operation.[0003]2. Description of the Related Art[0004]For a compressor equipped with a suction adjustment valve on the suction side of a compressor main body and a gas release valve on the discharge side thereof, the discharge capacity is adjusted by load / unload control operation in which when the pressure on the discharge side becomes high, the suction adjustment valve is closed and the gas release valve is opened, and when the pressure on the discharge side becomes low, the suction adjustment valve is opened and the gas release valve is closed.[0005]However, the above compressor cannot completely close a suction channel with the suction adjustment valve, even in case of unload operation in which compressed gas is not required on the consuming side. When the suction channel ...

AI Technical Summary

Benefits of technology

The present invention provides a screw compressor that reduces power losses under a state in which the supply of compressed gas is hardly required. This is achieved by a controller that switches between an on-state and an off-state of a clutch mechanism based on a discharge pressure value detected by a pressure sensor. When the discharge pressure value becomes higher than a predetermined unload set value, the controller switches the clutch mechanism to the off-state, disconnecting the driving machine from the compressor main body and reducing power losses. When the discharge pressure value becomes equal to or lower than a slightly lower value, the controller switches the clutch mechanism from the off-state to the on-state, or maintains the switched state until a predetermined time period passes. Additionally, the controller counts the number of times the clutch mechanism is switched to the on-state, and an alarm is generated when the number exceeds a predetermined threshold to prevent excessive wear of the clutch mechanism.

Problems solved by technology

However, the above compressor cannot completely close a suction channel with the suction adjustment valve, even in case of unload operation in which compressed gas is not required on the consuming side.

As a result, the operation cannot be continued, and, in the worst case, the compressor main body is damaged.

Thus, even in the unload operation, the suction adjustment valve cannot be completely closed, and 20 to 30% of the power that is consumed in load operation is unfortunately wasted.

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